I do not have a DSI unit, but a bunch of folks on the NWKA site who do have them shoot their DSI through their hulls and they all seem quite happy with the performance.
I would recommend that you try the foam puck type installation first. It is cheap, easy and then you can see how it works for you. If you are unhappy you can try the through scupper mount. For the initial foam puck testing you can just run the cables out your front hatch (no drilling required). BTW, I still run my cables out the front hatch, because if its not broken don't fix it
Fish tremble when they hear my name
A ship in harbor is safe -- but that is not what ships are built for.
--John A. Shedd, Salt from My Attic, 1928